PURPOSE: To improve creep resistance by specifying the composition of an alloy and dispersing fine particles of an intermetallic compound in a structure.
CONSTITUTION: The alloy has a composition consisting of, by atomic ratio, about 44-49% Al, about 0.3-4.0% Nb, about 0.25-3.0% Mn, about 0.1-<1.0% Mo, about 0.1-<1.0% W, about 0.1-0.6% Si, and the balance Ti and also has a structure where, after heat treatment, a particulate phase containing one or more elements among W, Mo, and Si is dispersed in θ-phase and α-2 phase. It is preferable to regulate the contents of W and Mo to about ≤0.9 atomic %, respectively. The cast alloy is subjected to hot isostatic pressing at 2100 to 2400°F and 10 to 25 ksi for 1 to 4 hr to block internal defects and then heat-treated at 1600 to 2400°F for 1 to 50 hr. By this method, the creep time until 0.5% elongation is reached can be doubled at 1200°F and trebled at temperatures higher than 1200°F as compared with that of a titanium alloy where TiB2 is dispersed.
PURABIIRU AARU BOOUERU
HAWAADO EFU MERITSUKU
AVCO CORP